Air purification systems are used to purify the polluted air inside the houses, buildings, clean rooms or any such premises. Such systems have series of filters for specific functions or some the systems have composite single filter for simplicity of the user to help to manage the purification system and to replace the filter.
The most commonly used filters are pre-filters or foam filters, particle removal filter and gas adsorption filter. Pre-filters with PP fibre mesh prevent the bigger dirt, dust particles, hairs getting trapped by other non-cleanable filters in the purification system. The PP fibre mesh filter generally is meant to be cleanable and washable.
Particle removal filters are made out of commercial HEPA (High efficiency particulate absorption) or some of them are made out of real HEPA material. Gas adsorption filters are Active carbon filters which are effective against harmful gases like Toluene, Formaldehyde, Benzene etc. Alternatively, there can be a single composite filter in place of separate particle and gas adsorption active carbon filter.
There are prior arts available which alerts the user to change the filter using few concepts. The most popular is based upon the pre-determine threshold volume of air that should pass through the filter. The volume of air that passes through the filter is a function of the RPM of the fan or the blower used in the system and the time for which the system is operating. So the filter life alert is direct function of the time for which the system is operated and the various speed setting, the system is operated.
There is also a prior art which compares the speed of the motor or the fan to the preset speed and then determines if the filter should be replaced or not. Practically all of these prior arts have limitation. The resistance of the filter for the flow of air through it varies from filter to filter. This has direct impact on the motor RPM. It is also a known fact that the motor in-itself has a tolerance of +/−10% on the RPM specification. With above variations of the filter and the motor parameters, the accuracy of the prior art is low. Further the electronics to measure the speed of the motor is also costly.
EP20090164084 to Woo Mu Seon et al. teaches a system and method for changing a filter provided in an air purifier that includes measuring rotational speed of the motor which rotates a fan to direct/inset air into the filter. This measured speed is then compared with an already pre-set value of the rotational speed. Besides, the time for which the motor is running at a particular rotational speed is further measured and compared with the pre-set time for which the motor should run at that speed. Based on these readings and comparisons made with pre-set values therein, the time to change the filter of air purifier can be determined.
US20040840758 to Kang Pengju et al. discloses a method and system for detecting and predicting air filter condition for an air handling system. Accordingly, the technique for detecting and predicting air filter condition of this invention uses a detection statistic to ascertain system resistance. Further, the remaining operable life of the air filter can be predicted therein. The system resistance is determined by using means to determine the approximate expected operation of the air handling system. This approximation is further compared to actual values to obtain a difference. This difference is still further compared with pre-decided threshold values such that if it is more than the threshold, an alarm is sounded, thereby indicating that there is a resistance to air flow. Hence, it can be predicted from this exercise that owing to resistance in air flow, the air filter shall be required to be changed.
There is a need of a filter detection based air purification system that firstly identifies and indicates if a particle removal filter is installed in the air purification system, and secondly if the protective cover on the filters is removed before installing the filter. A filter detection based air purification system is also needed that determines and indicates expiry of a particle removal filters in the system and that the old filter is replaced with a new identical filter.